Due to the continuing demand for computing and networking applications, there is a growing demand for high performance computing (HPC) platforms, as well as large data centers. In either case, the interconnects between computer servers or network nodes have not been able to keep up with the growth in computing power within the chip or server. The bottlenecks include, but are not limited to, chip-to-chip communication power, size and latency, as well as server-to-server communication power, size and latency. In more recent applications, optical fiber has been used as the physical link between the chips (or the servers) inasmuch as the bandwidth of the fiber is significantly greater than the standard copper interconnect.
The processing on a chip itself is generally performed using a parallel word that is multiple bits in width (a typical parallel word having a width of 8 bits, 16 bits, 32 bits or 64 bits). Transferring this information from a first chip and onto a second chip (or other element) usually requires the parallel word to be converted to serial form in order to reduce the pin count at the edge of the chip, where the physical packaging would otherwise need to deal with, perhaps, a large, parallel number of output leads.
As a result, a serialization process is usually performed at the edge of the chip, creating serial data from the parallel word. At the receive end of the communication path, a de-serialization function is required to re-format the incoming serial data stream back into the parallel word structure used within the chip on the receive side of the process. The combination of these serialization and de-serialization processes are often referred to in the art as “SERDES”. Additionally, the receive end of the system must perform clock recovery on the incoming serialized data stream in order to properly re-create the parallel word.
The SERDES and clock recovery processes are problematic in that they consume a significant amount of power, while adding latency to a process where high speed operation is demanded and expected.
Thus, a need remains in the art for an optical-based interconnect system with improved operational characteristics.